Utilizing Full Synthetic

[Supraman]

Hello,

Does anyone have experience with running Full Synthetic backup as daily vs running active full backup? Want I want to know is would there be any difference between in terms of speed and performance and would it actually make sense to use Full Synthetic as daily backup.

[Shestakov]

Hello Vinh,
Is your goal to have only one backup in the chain? You can just use Forever forward incremental to achieve the goal. Daily active full is superfluous. Thanks!

[foggy]

Performance depends on several factors, primarily target storage I/O capabilities. You can test it and see whether you're ok with longer everyday backups.

[Thernlund]

My configuration is as so...

• VB&R 8.0.0.817
• VB&R Server is a dedicated VM running Win2012R2
• VMWare ESXi 5.5 cluster
• All production VMs live on an EMC SAN
• VB&R VM lives on one of the cluster hosts directly
• Backup destination is a Synology RS2414+ loaded with WD Red drives
• EMC SAN is connected to cluster through multiple redundant links via Cisco switch
• Synology is connected via a single cable directly to the host where the VB&R VM lives (no switch, direct patch cable connection)
• Synology is set up as an iSCSI target in VB&R VM. It is dedicated to backups
• The full data set is ~4.5TB

The backup times I'm seeing are as follows...

• Incremental: ~1.0 hours
• Active Full: ~13.5 hours
• Synthetic Full: 30+ hours!!

My first question is... what the heck is up with the Synthetic Full? That's a pretty long time. I've watched the network IO on the iSCSI port and it runs about 500mbps in both directions simultaneously. I've been assuming it's simply the nature of the beast in my config. Did I just answer my own question? Or does this look like an issue I need to get involved with and call Support?

The bigger question I have... Given how quickly the Active Full completes (it actually shaved 2 hours off of what BackupExec was doing) is there any other reason I might want to be doing Synthetics? Up to this point I've just assumed synthetics were for situations where you had more time on your hands than network capacity. I personally have more capacity than time, so it would seem to me that I have no good reason to use Synthetic Fulls right now.

A lot of assuming here, I know. Sound thinking though? Or am I missing something?

Any advice is appreciated.


-T.

[Shestakov]

Hello Terry and welcome to the forums!

You are correct, synthetic fulls are designed right to decrease the load on production VMs. However they are much more I/O intensive so your target storage needs to be capable of increased I/O load. Also note that it's recommended to perform active fulls periodically to avoid chains corruption. So Active Fulls look like a choice for you.

You might also want to consider forever incremental method, which does not perform any periodic fulls at all and is among the best practices in a case you use Surbackup for recoverability testing. Thanks!

[nielsengelen]

In regards to your backup device, could you give some more info on the configuration? I see you have WD red drives, which raid are you using and how many disks in total?

[Thernlund]

Hello Terry and welcome to the forums!

You are correct, synthetic fulls are designed right to decrease the load on production VMs. However they are much more I/O intensive so your target storage needs to be capable of increased I/O load. Also note that it's recommended to perform active fulls periodically to avoid chains corruption. So Active Fulls look like a choice for you.

You might also want to consider forever incremental method, which does not perform any periodic fulls at all and is among the best practices in a case you use Surbackup for recoverability testing. Thanks!

Thank you for the response. Indeed I have considered Forever Incrementals. Buuut... such a thing makes me a little uneasy. I come from the old school way of thinking where you need to have full backups periodically to keep fewer links in the (fragile) chain. More links in the chain equal more points of weakness, no? What happens if this goes for a couple years? What if I lose an incremental waaay back in the chain, do I lose everything after it? My (antiquated?) wisdom tells me that I do.

Of course the way Veeam does it, while not completely foreign, is still a rather new concept to me. So if there's anything you could tell me to get me more comfortable with the "new math", I'd appreciate it.


EDIT: I just read the links you provided. I think I have a misunderstanding of what Forward Incremental Forever actually is. I'll have to read up on it.

EDIT2: Alright, I get it now. It inches the Full backup forward by merging the first incremental. This is similar to the creating a synthetic full every night, yes? Thus reappears my concern regarding the time synthetics take. Maybe not a problem though; merging one has to be faster than merging seven I expect. Maybe I'll give it a try.

In regards to your backup device, could you give some more info on the configuration? I see you have WD red drives, which raid are you using and how many disks in total?

Certainly. It's a Synology RS2414+ loaded with 12 WD Red drives. It's set up as an iSCSI target and it directly connected via a crossover cable to the host on which the VB&R server lives. The RAID configuration is something they call SHR (Synology Hybrid RAID). Info here... http://forum.synology.com/wiki/index.ph ... id_RAID%3F

I didn't really set it up like that on purpose. They just do that by themselves if you don't change it intentionally. For all I know, SHR is the heart of all my problems. Pff. Most inexpensive NAS devices try to think for you though, and this one isn't really different. But I'm only using it strictly for storing backups. No production data. For such a purpose I didn't want to spend upwards of $25k+ for an EMC or similar solution.

[foggy]

Most inexpensive NAS devices try to think for you though, and this one isn't really different. But I'm only using it strictly for storing backups. No production data.

Those typically lack good random I/O performance, so do not fit well for synthetic activity.

[Shestakov]

This is similar to the creating a synthetic full every night, yes? Thus reappears my concern regarding the time synthetics take. Maybe not a problem though; merging one has to be faster than merging seven I expect. Maybe I'll give it a try.

Your understanding is correct. Forever incremental method is a bit slower than simple incremental backup since it needs to merge 2 restore points daily, but doesn`t require to merge 7 points in the end of the week like in Synthetic method.
Thanks!

[Thernlund]

Thanks for the help!